This invention relates to the application of indicia to workpieces.
More particularly, the invention relates to the application of indicia to a surface of a moving workpiece.
Still more specifically, the invention relates to a method of and an apparatus for applying indicia to a surface of a moving workpiece.
Many types of moving workpieces must be provided with indicia which may be indicative of workpiece batch numbers, workpiece quality or the like. The invention will hereafter be described with respect to the application of indicia to a surface of a moving workpiece, particularly a rapidly moving workpiece such as a metal plate or a metal tape (e.g. a steel plate or steel tape), although it should be understood that the invention is by no means limited to this application.
It has been proposed in Ser. No. 910,277 to subdivide the surface of a workpiece (e.g. a plate or a tape) intermediate an inspection station and an indicia-applying station into zones having a length corresponding to the length of the indicia to be applied, whereupon each individual zone is electronically tracked intermediate the inspection station and the indicia-applying station, and the surface of each of the thus-tracked zones is oxidized and melted by the application of a laser beam from a laser light source. Each of the zones to be tracked is assigned a space in a shift register associated with the inspection station, and according to a preferred embodiment of this prior proposal the items of information from the individual shift registers are supplied to the laser light source simultaneously or sequentially to control the operation of the same, and simultaneously or in timed succession converted into laser-light pulses.
This prior proposal has been found to be highly advantageous in many applications. However, there are certain applications in which a more precise marking of e.g. faults in the tape or plate is necessary or at least desirable. For such applications, a further improvement is necessary.